Automatic draft regulated furnace



May 14, 1940. A. D. co1.; y 2,200,415

AUTOMATIC DRAFT REGULATED FURNACE gmc/Wto@ May 14, 1940., A. D. coLE AUTOMATIC DRAFT. REGULATED FURNACE Filed March v29, 1937 2 Sheets-Sheet- 2 nvcwto'o Arthur D. Cole minvws Patented May 14, 1940 UNITED STTES FFICE Application March 29, 1937, Serial No. 133,587 In Canada May 21, 1934 4 Claims.

My invention relates to furnaces and has for an object to provide a furnace in which the draft is directly controlled in accordance with the pressure in the combustion chamber of the furnace.

Another object of the invention resides in providing a furnace utilizing a pressure responsive draft regulator directly subjected to the pressure within the combustion chamber of the furnace.

A still further object of the invention resides in providing a draft regulator for a furnace hav-- ing a re doorway and nre door, said regulator being subjected to the pressure within the combustion chamber through the fire doorway.

Another object of the invention resides in providing a neck adapted to form an extension of the doorway and to which the fire door is attached and by means of which the draft regulator is subjected to the pressure within the combustion chamber.

A feature of the invention resides in constructing the draft regulator with a damper and a separate pressure responsive damper control for operating the damper and in mounting the damper control on the fire door and in communication with the combustion chamber through the fire doorway.

Another object of the invention resides in providing an adjusting mechanism for the damper control whereby the action of the draft regulator may be easily and quickly varied.

A still further object of the invention resides in providing a furnace utilizing a Stoker or other type of burner resulting in a variable fire in which the draft is maintained proper for all conditions of the fire.

Another object of the invention resides lin providing a construction whereby the draft regulator may be brought into communication with the combustion chamber without cutting a hole through the walls of the furnace forming the combustion chamber.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

4 In the drawings:

Fig. l is an elevational sectional view of a portion of a boiler illustrating an embodiment of my invention.

Fig. 2 is a plan sectional view taken on line 2-2 of Fig. l drawn to a larger scale and showing the parts in altered position.

Fig. 3 is an elevational sectional View taken on line 3-3 of Fig. 2 and showing the parts in `the same position as in Fig. 1.

Fig. 4 is an elevational View of a portion of a boiler illustrating the embodiment of a modification of my invention.

Fig. 5 is an elevational sectional view of the damper control of the form of the invention shown 5 in Fig. 4 and taken through the fire door of the boiler.

In the control of the draft for furnaces such as domestic and commercial heating plants, boilers and the like, it has heretofore been the prac- 19 tice to utilize a pressure responsive device which has been connected in the smoke pipe or exteriorly of the furnace and which is adapted to actuate or control the operation of a damper connected in the smoke pipe or the chimney. Such l5 devices are not entirely accurate due to the fact that the pressure within the combustion chamber where the amount of air is to be controlled does not always correspond with the pressure in the smoke pipe since the products of combustion usugg ally pass through tortuous passageways where heat exchange occurs before entering the smoke pipe and after leaving the combustion chamber. This is particularly true where an automatic stoker is used to fire the furnace or where an 25 oil burner having two or more sizes of flame is utilized. Furthermore fluctuations in pressure in the smoke pipe are not always transmitted to the combustion chamber so that needless Variation of the damper is procured. The present 30 invention overcomes all of these defects by providing a construction in which a pressure responsive damper control is utilized which is in direct communication with the combustion chamber and which is subject to the pressure within the 35 combustion chamber and which operates the damper in the proper manner regardless of varying resistance in the smoke passageways of the furnace.

For the purpose of illustrating the application 40 of my invention, I have shown in Fig. 1 a furnace indicated in its entirety by the reference numeral I5. 'I'his furnace comprises a return tubular boiler I6 of the so-called locomotive type which is provided with a cylindrical portion I9 integral 45 with a fire box I'I. The fire box I1 rests upon an ash pit section 20 which is directly mounted on the floor or foundation 2| on which the boiler is supported. The front wall of the boiler is indicated at 22 and is provided with a fire door- 50 way23 which communicates with the combustion chamber 24 of the boiler formed within the fire box II. A door frame 34 surrounds the doorway 23 and is attached to the front wall 22. In the front wall 25 of the ash pit section 20 is pro- 55 vided an ash pit doorway 26 by means of which access may be had to the ash pit 21 within the ash pit section 28. At the front of the boiler and opposite the upper tubes 28 of the boiler is provided a smoke box 3U which has attached to it a smoke pipe 29. 'I'his smoke pipe is placed over a nipple 3| on the smoke box 3l) and is connected to the chimney in the customary manner. A removable cover 32 gives access to the smoke chamber 33 within said smoke box` The furnace I5 is shown as provided with a coal stoker |10. This stoker comprises a re pot |1| disposed within the ash pit 21 and surrounded by a jacket |12 forming an air chamber |13 surrounding the fire pot. Air is led into the fire pot |1| through openings |14 in the same. A plate |15 surrounds the jacket |12 and rests on an angle |11 attached to the boiler proper. The coal used with the stoker is stored in a hopper |18 and is carried from said hopper to the fire pot |1| by means of a screw conveyor |19 operating in a tube IBI. Air under pressure is directed to the chamber |13 by means of a conduit |82 which is connected to a blower |83. The mechanism for operating and controlling the operation of the stoker forming no particular feature of the present invention has not been illustrated or described, though it can be readily comprehended that any construction such as is now well known in the art may be used for the purpose.

In order to prevent cutting a hole in the Walls of the fire box |1 which is exceedingly difficult with boilers of the locomotive type for the purpose of subjecting the damper control to the pressure in the combustion chamber 24, the following construction is employed.

Attached to the door frame 34 on the front wall 22 of boiler |5 is a neck 35 which is tubular in form but is open at its ends. This neck is constructed with an upper wall 36, a lower wall 31 and lateral walls 38 giving the said neck a box-like form. The neck 35 is of such dimensions that the same covers the opening of the doorway 23 and forms an extension or continuation thereof. The inner end of the neck 35 is constructed with a ange 39 which overlies the frame 34 and said neck and frame are provided with hinges and a latch, not shown, by means of which the neck may be attached to the frame 34. The outer end of the neck is constructed with a similar ange 4| against which the fire door 43 may be fitted. The neck 35 and door 43 are likewise provided with hinges and a latch not shown by means of which the fire door 43 is hingedly connected to the neck 35 and when open gives access to the combustion chamber 24 for the purpose of removing clinkers and inspecting the i'lre.

The invention embodies a draft regulator indicated in its entirety by the reference numeral 44. This draft regulator includes a damper 45 and a damper control 46 which will now be described in detail.

The damper control 46 includes a case 41 which comprises two spaced side walls 48 which are of the shape of a segment of a circle. These walls are parallel to one another and are attached to a substantially radial wall 49 (Fig. 3) which when the invention is installed extends substantially at right angles to the pipe and horizontally when applied to a vertical smoke pipe. The continuation of the wall 49 is provided with a curved or arcuate wall 5| which extends about the arcuate edges of the walls 48 and which terminates in an inwardly turned flange 52 extending toward the center of curvature of the wall 5|. The two walls 48 have extensions 53 which overlie the smoke pipe 29 and are clamped about said pipe by means of a bolt 5D. The portion of the case 41 opposite the wall 49 is arranged to provide an opening 54 by means of which the interior of the case is subjected to atmospheric pI'BSSllI'e.

Between the two walls 48 of case 41 and exteriorly of the smoke pipe 29 is disposed a vane 55. This vane is attached to a shaft 56 by welding or otherwise, which shaft extends through said walls and is journaled therein. The vane 55 is of such dimensions as to closely t between the two walls 48 and the shaft 56 is disposed at the center of the curvature of the wall 5| so that the vane 55 upon movement of shaft 56 may closely follow the surface of the wall 5|. By means of this construction the equivalent of a piston and cylinder is provided, vane 55 serving as the piston, and case 41 as the cylinder.

Within the smoke pipe 29 is disposed the damper 45 which is welded or otherwise secured to a shaft 58. Shaft 58 is journaled in the two extensions 53 and is so arranged as to be disposed across the middle of the smoke pipe. The damper 45 is slightly smaller than the smoke pipe so that the same may move into a position substantially closing said pipe or into a position such as shown in full lines in Fig.. 3 in which no obstruction to the ow of iiue gases through the smoke pipe results. In order to insert the damper in the smoke pipe 29 a slot 59 is cut in the said smoke pipe which is provided with a notched portion 6| in which the shaft 58 is disposed. This opening is closed by means of an arcuate band 62 which is attached to the extensions 53 of case 41` The wall 49 of said case is constructed with a flange 64 which iits about the band 62. A wall similar to the wall 49 and indicated at 65 is constructed with a similar iiange 66 which also fits about said band. Said wall is provided with a flange 61 which lies in the plane of the flange 52 and which in conjunction therewith forms a wall structure bounding the opening 54 and serving as stops which the vane 55 may engage. This wall closes the upper portion of the case 46 and encloses the vane 55 within case 41.

In the wall 49 of case 41 is provided a downwardly extending opening 68. A duct 69 provided with a flange 1| is attached to said wall and is in communication with the chamber 12 formed within case 41 through the opening 68. This duct is adapted to be attached to a nipple 13 formed on the wall 36 of neck 35 which nipple is in communication with the doorway 23 leading to the combustion chamber 24. It will thus be seen that the vane 55 is subjected on one side to atmospheric pressure through the opening 54 and on its other side to the pressure within the combustion chamber 24 through opening 68, duct 69 and the doorway 23.

The vane 55 operates the damper 45 in the following manner: Attached to the two shafts 56 and 58 are two pulleys 14 and 15. A chain 16 passes over these pulleys and is attached at a certain locality to each thereof. These pulleys are of proper diameter so that when the vane 55 travels throughout its path of movement, the damper 51 will be moved from a position parallel with the smoke pipe 29 to its closing position. The end of shaft 56 to which pulley 14 is attached is bent to provide an arm |16.4

This arm has adjustably attached to it a counterweight |88 by means of which the vane 55 may be balanced.

Attached to the end of the shaft 55 opposite to that to which the pulley 14 is secured is a segmental pulley 11 best shown in Fig. 1. This pulley has secured to it a chain 18. Chain 18 is pivoted to a beam 19 which in turn is pivoted to a fulcrum 8| secured to case 41. This fulcrum is provided with a number of notches 82. A slidable poise 83 is mounted on the beam 19 and is adapted to engage in any of the notches 82. Beam 19 is formed with an extension 89 on the other side of the fulcrum 8| which permits of moving the poise 83 up to and past the fulcrum 8|. By this means the vane 55 may be counter-balanced or over or under counterbalanced so that the device will operate with any suction within the combustion chamber 22.

The operation of the invention is as follows: 'I'he poise 83 is adjusted to the proper notch 82 to give the desired draft or suction in the combustion chamber 24. When the draft in the chimney corresponds therewith, the vane and damper occupy the position shown in full lines in Fig. 3. In the event that the draft inthe smoke pipe increases and the suction in the combustion chamber 22 correspondingly increases, vane 55 is drawn downwardly in opposition to the poise 83 and the damper 51 is partly closed as shown in dotted lines in Fig. 3. This forms an obstruction in the pipe 29 to the flow of flue gases through the smoke pipe 2| and the suction in the combustion chamber 22 is correspondingly reduced. An adjustment by means of this construction is procured whereby a balance is reached giving the desired suction in the chamber 24.

In Figs. 4 and 5 I have shown a modification of the invention in which the damper control is directly attached to the firing door of the furnace instead of to the smoke pipe. Inasmuch as the construction of the damper control shown in this form of the invention is substantially the same as that illustrated in Figs. 1, 2 and 3, the description of the corresponding parts will not be repeated and the same reference numerals preceded by the digit l will be used to designate the corresponding parts.

This form of the invention may be used with any type of furnace and for this reason the furnace has not been shown in detail. The furnace illustrated is designated by the reference numeral and consists of a `boiler disposed within a suitable wall structure ||8. Within this wall structure is provided an ash pit and a combustion chamber, not shown, to which access may be had through a suitable fire doorway and ash pit doorway closed by a fire door |43 and an ash pit door |28. The flues of the boiler are accessible through another opening closed by a flue door |3|. All of these doorways are formed in a front |21 mounted at the forward portion of the wall structure ||8 and the doors |43, |28 and |3| are removably attached to said front. At the uppermost portion of the furnace is a smoke pipe |29 which communicates with the smoke chamber of the furnace.

It will be readily comprehended that the form of the invention shown in Figs. 4 and 5 may be equally as well installed on a boiler of the type shown in Fig. 1.

In the form of the invention shown in Fig. 4 the neck 35 is dispensed with and the firing door |43 mounted in the usual manner upon the front |21 of the furnace proper. Case |41 in this form of the invention is constructed with a neck 84 formed by the walls |49, |48 and |65 which walls are provided with flanges 85 adapted to be bolted to the door |43 by means of bolts 86. 'Ihe neck 84 provides a passageway 81 which communicates through an opening 88 in the door |43 with the combustion chamber of the boiler. The damper |51 is mounted in the smoke pipe |29 the same as in the other form of the invention, except that the shaft |58 is directly journaled in the Walls of the smoke pipe instead of the case |41.

1n this form of the invention a complete pulley 89 is used instead of the pulley 11 Which is attached to the shaft |56. This pulley has Wrapped about it a cable 9| which has attached to one end of it a weight 92. Said cable passes over another pulley 93 secured to a bracket 94 which is attached to the furnace proper. This cable is further wrapped about another pulley 95 secured to shaft |58 for damper |51 and has attached to the extreme end of it another weight 96. It will be readily comprehended that by the proper adjustment of the Weights 92 and 96 which are formed of a number of washers indicated at 91 and attached to cotter keys 98, the proper counter balancing of the vane |55 can be procured and operation of the damper brought about the same as with the other form of the invention.

Although I have shown my invention as applied to a certain type of boiler, it can be readily comprehended that the invention may be utilized with a hot air furnace or any type of a furnace or heating plant and oil or gas burning furnaces. Likewise the device may be utilized with a furnace having the smoke pipe at some other locality than that shown.

The advantages of my invention are manifest. The device is made responsive to the draft conditions at the source of the fire instead of at some remote locality which may or may not have draft conditions corresponding to the actual draft conditions at the fire. In this manner proper draft can be had with variable rates of combustion as results in stoker red furnaces and multiple flame oil burning furnaces. The device is extremely simple in construction and is positive and elfective in operation. The invention is not affected by variations in pressure in the smoke pipe which never reach the combustion chamber of the furnace where the regulation is desired.

Changes in the specific form of my invention, as herein disclosed, may be made within the scope of what is claimed without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In a furnace, a fire box providing a combustion chamber, said re box having a ring doorway therein, a neck open at its ends, said neck being adapted to cover said doorway and extending outwardly from said re box, said neck having a laterally disposed opening therein, a fire door mounted on said neck and closing the outer end thereof, means forming a passageway for gases of combustion, said passageway communicating with said combustion chamber, a damper in said passageway, a pressure responsive damper control for operating said damper, said control being connected to said neck and being subjected to the pressure within the combustion chamber through the lateral opening in the neck.

2. In a furnace, a fire box providing a combustion chamber, said fire box having a firing doorway at the front thereof, a box-like neck having upper, lower and lateral walls and open at its end,

said neck being arranged to cover said doorway and extending outwardly therefrom, the upper wall of said neck having an opening therein, a fire door mounted on said neck and closing the outer end thereof, a smoke pipe at the front of said re box communicating with said combustion chamber, a damper in said smoke pipe, a pressure responsive damper control for operating said damper disposed at the front of the furnace, said control being in communication with said combustion chamber through the opening in said neck.

3. In a furnace, a fire box providing a combustion chamber, said re box having a ring doorway at the front thereof, a box-like neck having upper, lower and lateral walls and open at its end, said neck being arranged to cover said doorway and extending outwardly therefrom, the upper wall of said neck having an opening therein, a fire door mounted on said neck and closing the outer end thereof, a smoke pipe at the front of said re box communicating with said combustion chamber, a damper in said smoke pipe, a pressure responsive damper control mounted on said smoke pipe and operating said damper, and a duct between said damper control and the opening in the upper Wall of said neck.

4. In a furnace, a re box providing a combustion chamber, said fire box having a firing doorway therein, a member covering said doorway and having two openings therein, a closure movably mounted on said member for opening and closing one of said openings, means forming a passageway for gases of combustion, said passageway communicating with said combustion chamber, a damper in said passageway, a pressure responsive damper control for operating said damper, said control being connected to said member and being subject to the pressure within the combustion chamber through the other of said openings.

ARTHUR D. COLE. 

